1. Field of the Invention
The present invention relates to a zoom lens having a camera-shake compensation function, that is, a function of correcting a blur in a constructed image derived from a vibration of a camera, and an imaging apparatus employing the zoom lens. More particularly, the present invention is concerned with a zoom lens that is compact enough to be preferably adopted as an imaging optical system to be included in a digital still camera, a digital video camera, or any other digital input/output equipment, that highly precisely varies a power, and that has a camera-shake compensation function, and an imaging apparatus employing the zoom lens.
2. Description of the Related Art
In recent years, a digital still camera and other types of imaging apparatuses employing a solid-state imaging device have prevailed. Higher image quality is demanded along with the prevalence of the digital still camera. In particular, the digital still camera employing an imaging device which offers a large number of pixels is requested to include an imaging lens or especially a zoom lens that enjoys perfect image formation and suits the solid-state imaging device which offers a large number of pixels.
In particular, there is an increasing demand for a camera-shake compensation function that prevents a blur in a constructed image derived from a vibration made during imaging.
In addition, the demand for a compact design is intense. A zoom lens that is especially compact in the direction of the depth thereof, that is, the incident optical-axis direction is needed.
For example, Japanese Unexamined Patent Publication (JP-A, hereinafter) No. 224160/1993 describes a zoom lens including a first group of lenses that is positively refractive, a second group of lenses that is negatively refractive, a third group of lenses that is positively refractive, a fourth group of lenses that is positively refractive, a fifth group of lenses that includes a group of positive lenses and a group of negative lenses and that is negatively refractive as a whole. In the zoom lens, a camera shake is compensated by moving the group of negative lenses, which belongs to the fifth group of lenses, in directions perpendicular to the optical axis of the zoom lens.
On the other hand, an optical system is bent by inserting a prism among lenses in attempts to downsize the optical system in an incident optical-axis direction. For example, an optical system or a zoom lens described in JP-A No. 238318/1996 has the optical axis thereof bent by disposing a prism among four groups of positive lenses, negative lenses, positive lenses, and positive lenses, and is thus downsized in the incident optical-axis direction.